Yeah, keeping the ISO low is good but there will be situations that are better to have the shots with higher ISO than nothing. For example indoor with low light and no flash.
I am hoping there is some preset manual we can store and then switch between them. I tried and realized it can only store other settings. Anyway, to switch between the presets, you still need to go to the menu. Since there, you can set Iso from auto to manual.
I will explore can this be dine with the assigned button. That would be great without having to go into the manual setting.